1. Field of the Invention
This invention relates generally to management of external devices in computer server systems. More specifically, this invention relates to a system and method for monitoring external devices in a computer server in both operational and power-off conditions.
2. Description of the Related Art
In the server management industry, it is desired to manage all of the internal devices of computer systems, as well as the external small computer systems interface (SCSI) devices such as SCSI storage subsystems at all times, regardless of whether the computer system is in a power-up state. The SCSI Accessed Fault-Tolerant Enclosures (SAF-TE) specification provides a standardized method to monitor and report status information on the condition of disk drives, power supplies and cooling systems used in high-availability servers and storage subsystems. In contrast to monitoring component status through serial lines or reserved SCSI signaling methods, a SAF-TE-compliant enclosure typically implements the enclosure as an assignable SCSI target identification using a SCSI chip and microcontroller. The microcontroller is used to control various alarm sensors, status lights, and displays within the enclosure. The enclosure""s SCSI target ID is polled periodically by the SCSI controller to determine status, thereby allowing rapid notification in the event fault tolerance is lost due to component failure. The SAF-TE specification provides information about drive presence, conditioning of drive slots for insertion or removal, power-supply voltage, fan speed, door-lock status, and drive-usage statistics.
Most microprocessor-based computer server systems include an embedded management controller (EMC) connected to a host central processing unit (CPU) through a local bus. The EMC is used to control various internal and external components such as thermal sensors, fans, disk drives, and a SCSI backplane.
The EMC operates on system power when the computer system is powered up, and on standby power when the computer system is powered down. The problem is that the SCSI support is only available when the computer is up and running. When the system is powered down, the management information for the external SCSI components cannot be accessed.
It is therefore desirable to provide a system for monitoring external peripheral components connected to the computer system at all times.
In one embodiment, the present invention provides a method of monitoring peripheral devices connected to a computer system that includes coupling a first data bus to communicate information between an external monitoring system and the computer system; coupling a second data bus to communicate data between a peripheral device and the computer system; and coupling a switch mechanism between the first data bus and the second data bus, the switch mechanism being operable to allow signals from the first data bus to be communicated over the second data bus when operating power to the computer system is off.
In one embodiment, coupling the switch mechanism includes coupling a first switch between the first data bus and the second data bus; and coupling a second switch to inhibit communication between the peripheral device and the computer system when operating power to the computer system is off.
In another embodiment, the first data bus is a serial data bus, such as an I2C bus, that transmits a data signal and a clock signal, and the second data bus is a parallel data bus, such as a SCSI bus. The first switch and the second switch are coupled to allow the data, clock, and ground signals to be transmitted over the second data bus when the first switch is on and the second switch is off.
One application for the present invention includes monitoring operating parameters in an external subsystem coupled to a computer system when the computer system is not receiving operating power. System management information is communicated from the external subsystem to a monitoring component in the computer system over the second bus when the computer system is receiving operating power. When the computer system is not receiving operating power, the operating parameters are communicated to the computer system over the first data bus.
To accomplish this in one embodiment, a first switch is coupled between the first data bus and the second data bus; and a second switch is coupled between the peripheral components and the second data bus. The first switch is controlled to allow signals from the first data bus to be communicated to the computer system when operating power to the computer system is off, and the second switch is controlled to inhibit communication from the peripheral device on the second data bus when operating power to the computer system is off.
In a further embodiment, a third switch is coupled between the second data bus and the monitoring component; and communication from the second data bus to the computer system is inhibited when operating power to the computer system is off by coupling a fourth switch between the second data bus and the computer system.
The method, as set forth in claim 10, wherein the first data bus is a serial data bus that transmits a data signal and a clock signal.
In another embodiment, the present invention provides an apparatus for monitoring a computer system including a first data bus coupled to communicate information from one or more monitoring systems in the computer system, a second data bus coupled to communicate information from one or more peripheral devices in the computer system, and a switch mechanism coupled between the first data bus and the second data bus. The switch mechanism is controlled to allow signals from the first data bus to be communicated over the second data bus when operating power to the computer system is off.
In another embodiment of the apparatus, the switch mechanism includes a first switch connected between the first data bus and the second data bus, and a second switch connected to inhibit communication from the peripheral devices in the computer system when operating power to the computer system is off. The first switch and the second switch are coupled to allow all required signals, such as a data, clock, and ground signal, to be transmitted over the second data bus when the first switch is on and the second switch is off.
The present invention may be used to transmit a data signal and a clock signal from a serial bus over a parallel data bus so that external peripheral components may be monitored by an EMC that is operating on standby power.
The foregoing has outlined rather broadly the objects, features, and technical advantages of the present invention so that the detailed description of the invention that follows may be better understood.